title: Key events during the transition from rapid growth to quiescence in budding yeast require posttranscriptional regulators.
abstract: Yeast that naturally exhaust the glucose from their environment differentiate into three distinct cell types distinguishable by flow cytometry. Among these is a quiescent (Q) population, which is so named because of its uniform but readily reversed G1 arrest, its fortified cell walls, heat tolerance, and longevity. Daughter cells predominate in Q-cell populations and are the longest lived. The events that differentiate Q cells from nonquiescent (nonQ) cells are initiated within hours of the diauxic shift, when cells have scavenged all the glucose from the media. These include highly asymmetric cell divisions, which give rise to very small daughter cells. These daughters modify their cell walls by Sed1- and Ecm33-dependent and dithiothreitol-sensitive mechanisms that enhance Q-cell thermotolerance. Ssd1 speeds Q-cell wall assembly and enables mother cells to enter this state. Ssd1 and the related mRNA-binding protein Mpt5 play critical overlapping roles in Q-cell formation and longevity. These proteins deliver mRNAs to P-bodies, and at least one P-body component, Lsm1, also plays a unique role in Q-cell longevity. Cells lacking Lsm1 and Ssd1 or Mpt5 lose viability under these conditions and fail to enter the quiescent state. We conclude that posttranscriptional regulation of mRNAs plays a crucial role in the transition in and out of quiescence.
authors.affiliation: Basic Science Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109.
authors.forename: Lihong
authors.initials: L
authors.lastname: Li
authors.forename: Shawna
authors.initials: S
authors.lastname: Miles
authors.forename: Zephan
authors.initials: Z
authors.lastname: Melville
authors.forename: Amalthiya
authors.initials: A
authors.lastname: Prasad
authors.forename: Graham
authors.initials: G
authors.lastname: Bradley
authors.forename: Linda L
authors.initials: LL
authors.lastname: Breeden
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D060049:Asymmetric Cell Division / Q000187:drug effects; D002244:Carbon / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000235:genetics; D005434:Flow Cytometry; D040582:Inheritance Patterns / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D004718:Saccharomycetales / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D013696:Temperature; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D004272:DNA, Mitochondrial; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D002244:Carbon